I recommend checking your Apache error log, and then reposting your message, along with anything you learn from the error log, on the Installation and Configuration forum rather than this one.
Here is the log of the discussion with the webhost admin :
Selina Brown: Your script located at <A id=L2352189625865111366 onclick="window.open('http://www.mail-archive.com/php-bugs@lists.php.net/msg33826.html'); return false;" href="javascript:void(0);">http://www.mail-archive.com/php-bugs@lists.php.net/msg33826.html is using more memory.
Selina Brown: Hence, you are getting that error message.
Selina Brown: According to you this the xml file you are using more memory and the size is 2KB.
Selina Brown: Our engineer has increased the maximum memory limit for your account as 32MB.
Selina Brown: Please check your scripts and modify them so that it uses less resources.
Selina Brown: There is only one xml file in your account which is at htdocs/upload/extension/ezpaypal/package.xml. Selina Brown: To resolve your issue you need to modify your scripts so that it uses less resources.
32mb may not be enough, i would use a minimum of 64mb for ezpublish, however your shared web host may not like that.
you could try overwriting the memory_limit php value with .htacess, something like
php_value memory_limit 64M of course your web host may have overrides disabled.